Electronic display systems are commonly used to display information from computers. Typical display systems range in size from small displays used in mobile devices to very large displays visible to thousands of viewers. Large displays are sometimes created from tiling smaller display devices together. For example, video walls using multiple video displays are frequently seen in the electronic media and flat-panel displays are tiled to create larger displays. Multiple projector systems used to create a large, tiled, high-resolution display are also available.
A projector system utilizing basic projection units connected separately to each tile is described in U.S. Pat. No. 5,956,000, issued Sep. 21, 1999 to Kreitman et al. As an alternative design, U.S. Pat. No. 5,889,568, issued Mar. 30, 1999 to Seraphim et al. describes a system in which the individual control lines for each tiled display unit are connected to a central controller through interconnections on adjoining tiles. Yet another design is illustrated in FIG. 8 of WO 94/17637, published Aug. 4, 1994 by Lewis wherein an electronic control system receives one or more video input signals, digitizes the input video signal, and provides a digitized signal to each of a plurality of video display units. In each of these designs, a direct connection is made from a controlling device to each display tile individually. This kind of point-to-point connection is efficient and simple for small numbers of tiles but becomes impractical with larger numbers of tiles. Both wiring concerns and control issues become problematic since they continually increase as the number of tiles increases. Moreover, the design described in U.S. Pat. No. 5,889,568, referenced above, requires a back plate common to all of the tiles and it is quite difficult to replace faulty tiles. This makes the production and maintenance of large systems difficult and expensive. In addition, the designs described must be adjusted for each possible system size and are not readily expanded or configured.
U.S. patent application Ser. No. 2001/0038387 A1, published Nov. 8, 2001 by Tomooka et al., discloses a tiled display that employs packetized communication over a common bus to achieve a display interface that can accommodate new and larger displays without the need for redesign. Each display panel in the tiled display is provided with a panel control chip and a panel memory connected to the panel control chip. Referring to FIG. 2, the tiled display disclosed by Tomooka et al. includes a display controller 12 which receives image data from a source of image data 14, packetizes the image data and transmits the data packets to a plurality of display tiles 10 over a common bus 13.
A problem with this approach is that as the size of the tiled display grows larger, the overhead associated with the use of packetized communication on a common bus becomes a bandwidth limitation. Additionally, the physical implementation of a common bus in a tiled array becomes problematic as the number of tiles connected to the common bus increases.
There is a need therefore for an improved tiled display system that overcomes the problems noted above.